Ink extenders and inks utilizing organic based resins

ABSTRACT

An extender for flexographic and other ink compositions and inks using such extender where potato starch serves as the ink carrier and an emulsion resin. The use of potato starch provides for a readily available, cost effective, substantial and environmentally friendly alternative to petroleum and soy based resins.

TECHNICAL FIELD

This invention relates generally to ink compositions for printing andthe like, and more particularly to an ink composition that utilizesorganic based resins, namely potato starch.

BACKGROUND

Virtually all consumer products are sold in packages, such as cardboardcartons, boxes, and other types of containers. A package has two verydistinguishing features: a structural design and a graphical design. Thestructural design of a package is defined by the package's structuralfeatures, such as the dimensions, geometric shape, and material of thepackage. The graphical design of a package is defined by the colors,artwork, and other images applied thereto. The graphical designpreferably identifies the packaged product in a manner which isaesthetically appealing to potential consumers.

A package is typically formed from a sheet of corrugated board, cartonboard, or other work material upon which a graphical design is applied.The graphical design may be applied by many known processes. Forexample, a sheet having a design may be laminated to the package, or thepackage itself may be printed.

One common printing method is that of flexography. A flexographic printis made by creating a positive mirrored master of the required image asa 3D relief in a rubber or polymer material. Flexographic plates can becreated with analog and digital platemaking processes. The image areasare raised above the non-image areas on the rubber or polymer plate. Theink is transferred from the ink roll which is partially immersed in theink tank. Then it transfers to the anilox roll (or meter roll) whosetexture holds a specific amount of ink since it's covered with thousandsof small wells or cells that enable it to meter ink to the printingplate in a uniform thickness evenly and quickly (the number of cells perlinear inch can vary according to the type of print job and the qualityrequired). To avoid getting a final product with a smudgy or lumpy look,it must be ensured that the amount of ink on the printing plate is notexcessive. This is achieved by using a scraper, called a doctor blade.The doctor blade removes excess ink from the anilox roller before inkingthe printing plate. The substrate is finally sandwiched between theplate and the impression cylinder to transfer the image.

Components of the composition of a flexographic ink may include but arenot limited to: a vehicle such as a solvent or water; a coloring elementsuch as a pigment, pigment grinding, and letdown vehicles in colloidal,solution, or emulsion form; and other components which may include butare not limited to wax, pH control agents, viscosity modifiers,antifoamers, dispersants, antimicrobial agents, ink transfer agents, anddrying speed modification agents. The vehicle may contain a combinationof acrylic, maleic, fumaric, or other resins.

Water based flexographic inks typically contain acrylic polymers to givethe ink good transfer, stability, and resolubility when applied to asubstrate, such as corrugated board on constituent linerboard. Theacrylic polymers are conventionally produced from petroleum feedstock.Use of such acrylic polymers introduce several concerns, including: 1)the supply and pricing of petroleum is quite volatile and subject todisruption from external events 2) petroleum is a fossil fuel availablein finite quantities, i.e., it is a non-renewable resource and itssupply cannot be sustained indefinitely 3) the use of fossil fuelsincreases carbon footprint and subsequent environmental damage.

Alternative polymers to petroleum based acrylic polymers used in inksare available and known in the industry. One prime example of anon-petroleum based ink polymer is soy protein. However, use of soyprotein as a biofuel and foodstuff compete with its use in flexographicinks and such other uses are economically preferred. As with petroleumbased polymers, this also gives rise to significant fluctuations insupply and pricing.

Therefore, there exists a need for a polymer that is renewable andotherwise environmentally friendly, can be easily sourced and is notsensitive to fluctuations in pricing due to supply and demand from otheruses.

BEST MODE FOR CARRYING OUT THE INVENTION

Potatoes grown in the United States and most other countries aregenerally grown for food. In addition to being sold whole, potatoes areprocessed into a variety of food products. One byproduct of such potatoprocessing is potato starch. Starch water is created when potatoes arecleaned, sliced, diced and cut, with high pressure water, into familiarshapes as French fries or potato chips. Some potato processing plantsship starch water directly to downstream users or refiners in large tankcars. Potato plants located further away from secondary users, produce aconcentrated starch semi-dry product that is more economical to ship.

As reclaimed potato starch is a by-product of food processing forpotatoes that are grown are for human food consumption, the starch doesnot alternatively compete for its use as a bio based fuel or directlyinto industrial markets. Industrial starches have primarily threesources the largest is corn, second potato and third tapioca (sourced inAsia, Africa, So. America). Of the three, only raw potato starch in theU.S. is a by-product of food potato processing. Corn and tapiocasupplies go directly into industrial starch products or, depending uponsupply and market conditions, may be diverted into bio-fuels, food/feedproducts, or pharmaceuticals. Corn used in starch manufacturing directlycompetes with food and feed use of harvested corn. The competing uses ofcorn divert the supply into and out of markets depending upon thepricing pressures at that time. Recently, when corn became a valuedresource for biofuels, the supply of corn into food/feed marketsdecreased and prices increased. Therefore polymer derived from potatostarch overcomes the disadvantages of both petroleum-based andsustainable (i.e., soy-based) polymers previously discussed herein.Further, if secondary users, such as producers of potato starch basedpolymers, did not take away the starch water, the potato plants wouldhave a waste disposal issue and incur additional waste treatment costsas well as not being able to capture the added value of the raw materialas a sellable commodity. It should also be noted that potato starch doesnot contain or is formed from VOCs (volatile organic chemicals) andproducts utilizing potato starch are recyclable and repulpable, as wellas, compostable and biodegradable. It should be noted that use of potatostarch within the printing industry has been confined to applications onthe printing substrate—e.g., paper—and has not been used as part of anink or other printing composition.

The potato starch is used as part of the “extender” (e.g., non-pigment)portion of the ink composition, in lieu of petroleum-based or othernon-renewal polymers. In one embodiment, the extender formula is made upof:

Potato Starch 30.88% (by weight of total extender) MEA 3.86(mono-ethanol amine) Solution Resin 12.02 Antifoam 0.03

The components are mixed together, batch analyzed and then further mixedwith the following additional components to achieve the final inkextender composition:

Solven 13.35 (percent of total extender) Potato Starch 39.69 Antifoam 0.07 Antimicrobial  0.10

The extender portion of the present invention should contain at least48% weight percent of potato starch, and preferably 48 to 96% weightpercent, based on the total weight of the extender composition. Thepotato starch functions as a carrier and an emulsion resin in the finalink composition, as such emulsion resins are used and understood in theart. One commercially available brand of potato starch that we havefound provides superior results for the disclosed application isWestcote 3090 (Western Polymer Corp., Moses Lake, Wash.). Thisparticular starch formulation is highly substituted (having manyhydrophilic groups attached to the polymer backbone) and has qualities,such as high peak viscosity and evenly substituted molecules that tendto hydrate at the same time, that are well suited for use in thedisclosed ink applications. Nonetheless, while Westcote 3090 is apreferred starch, most any type of potato starch may be used for theapplications discussed herein.

The final ink should have a pH of from 9.0 to 10.0, preferably 9.5 to9.9. A basic compound, such as an amine, may be added to adjust the pH.Monoethanol amine is a preferred amine that increases pH of theextender. One antifoam agent that can be utilized is DF-66 (AirProducts, Allentown, Pa.). One antimicrobial that may be used is Nuosept498 (International Specialty Products, Wayne, N.J.).

The extender should contain at least 6% weight percent solution resin,preferably 12 to 24% weight percent. The solution resin is a polymerthat is soluble in water and assists in transferring a smooth andcontinuous layer of ink during the printing process. It also allows theink composition to be cleaned up relatively easily with water in a driedor wet state. One solution resin is UNI-REL 8170, produced by ArizonaChemicals of Jacksonville, Fla.

A final ink composition comprises a pigment dispersion with the extenderand other constituent components known in the art. One such example is:

Ink extender: 29.0% (by weight of final ink composition) Pigmentdispersion 57.5 Wax 1.5 Polypropylene Glycol 1.0 Solvent 11.0

The final ink composition should contain at least 25% weight percent ofthe ink extender, and preferably between 29 to 60% weight percent.

Pigment dispersion are generally sold commercially as the coloredpigment dispersed with soy protein. Of course, such pigments areprovided in a variety of colors, tones and hues, depending on the needfor the final ink color. The pigment dispersion should be included in anamount of at least 3% by weight, preferably from 8 to 60%, dependingupon the color desired. An aqueous pigment dispersion is preferred forease of handling. Other pigment formulations, whether disbursed orotherwise, as known in the art may be used.

One wax that may be used is Ultra Lube D-806 (Keim-Additec Surface USA,Wilmette, Ill.). Wax is included at a preferably amount of 1 to 5% byweight of the final ink composition. Polypropylene glycol is present atpreferably 1 to 5% by weight.

The viscosity of the ink composition, as measured in a No. 2 SignatureZahn cup, should be at least 18 seconds, and preferably ranges from 18to 28 seconds. Water is preferably used as the solvent in both theextender and the final ink composition, but other solvents may be used,thought non-aqueous solvents may detract from the environmental benefitsof the composition disclosed herein.

While particular embodiments of the invention have been described indetail herein, it should be understood that various changes andmodifications may be made in the invention without departing from thespirit and intent of the invention as defined by the appended claims.While the invention has been described with reference to a preferredembodiment, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the invention without departing from its scope.Therefore, it is intended that the invention not be limited to theparticular embodiment disclosed, but that the invention will include allembodiments falling within the scope of the appended claims.

1) An extender for an ink composition, the extender comprising: a)potato starch; b) a mono-ethanol amine; and c) a solution resin. 2) Theink composition extender of claim 1 wherein the potato starch comprisesat about 48% to 96% by weight of the total extender. 3) The inkcomposition extender of claim 1 wherein the potato starch is of a highlysubstituted form. 4) The ink composition extender of claim 1 furthercomprising a solution resin. 5) The ink composition extender of claim 1wherein the potato starch has high peak viscosity and evenly substitutedmolecules. 6) An admixed ink composition comprising: a) an extendercomponent comprising at least about 48% by weight of a potato starch insaid extender component; b) a pigment; and c) a solvent. 7) The inkcomposition of claim 6 wherein the extender comprises at least about 25%by weight of the total ink composition. 8) The ink composition of claim6 further comprising a wax and polypropylene glycol. 9) The inkcomposition of claim 6 further comprising a mono-ethanol amine in saidextender component. 10) The ink composition of claim 6 having aviscosity of about between 18 to 28 seconds as measured in a No. 2Signature Zahn cup test.